Information playback systems frequently utilize a stylus for reading signals from the surface of an information record, typically a plastic disc, that contains stored video and audio information. In some systems the information record has a fine spiral groove to guide the tip of a stylus that contains a thin electrode. In these systems, the stylus tip is made of a material having sufficient hardness to withstand the abrasion caused from tracking the groove. Materials which possess such hardness, for example diamond, generally have a crystallographic structure which presents surfaces exhibiting different qualities depending upon which crystallographic planes the surfaces are oriented along. Consequently, in manufacturing styli from these crystallographic materials for use in video disc playback systems, it is important to know and maintain the tip orientation during the various processing steps in order to achieve uniform styli of high quality.
The stylus tip is typically fabricated from a relatively small stone, e.g., a diamond stone, which is supported in a work holder during the processing steps. Such a work holder should be capable of firmly holding the stone, but still provide for ease of insertion or removal of the stone. The present invention provides a novel stone-positioning apparatus and method which meets the aforementioned criteria, and also facilitates the rapid positioning of the stone during the various processing steps, including crystallographic orientation and microscopic inspection of the stone.